Help choosing system for ADT2004

Dear Group:
I am planning to run ADT 2004 on one of two systems. I think both have limitations and so does my budget right now. Can someone help me with which one would be better:
Dell Dimension Desktop, P4 2.2gHz, 400mHz front side buss, 768mb (perhaps a bit more) ram, 40gb HD. The "video card" is called "integrated Intel 3d extreme graphics" and the available slots for a better card are PCI. It came with a flat panel 17" monitor. I got a really, really good price.
OR
A machine with dual 450mHz Xeon processors, not sure which video card but I could get another one, the slots are AGP I think, 1gb ram. This one is free from a reliable friend, but I would need to buy a flat panel monitor and possibly a video card.
I understand that the Dell described above has significant speed drawbacks in 3d, that the 3d circuitry is really not good enough but that the right card could MOSTLY solve them and that 400mHz front side buss is no longer the standard but is not too much of a draw back.
The only thing I know about the Xeon based machine is that the processors will probably not run multithread for ACAD so that I will get 450mHz of speed, not 900.
Also, I would probably want to run Photoshop and possibly Form Z at the same time.
Any advice would be most appreciated.
Thanks,
Michael

Opps,
It turns out that ADT has somewhat higher requirements than Acad 2004 and I chose the the two systems described in the message below based on the Acad requirements. Am I in even more 3d trouble now?
Thanks,
Michael
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later
in article BBF7E640.11C284% snipped-for-privacy@earthlink.net, Michael Meric at snipped-for-privacy@earthlink.net wrote on 12/6/03 8:02 PM:
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IMO go with the first one but.......... spring thru Dell for the graphics card now
wrote on 12/6/03 8:02 PM:
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